The mayor of Caracas has gone missing, according to reports.
Antonio José Ledezma Díaz, founder of the Fearless People's Alliance party, is believed to have been taken away from his home by the the Bolivarian National Intelligence Service (Sebin), an intelligence agency in Venezuela.
In a tweet posted in the early hours of Tuesday morning (1 August), Vanessa Ledezma, daughter of the mayor, claimed Sebin "took away her father. Help!"
She also posted a video believed to be showing the moment her father was taken away.
In another tweet, she said she held Venezuela's President Nicolás Maduro responsible for "my father's life".
She then said she wants the whole world to know that her father had been taken by Sebin members.
The detention of Ledezma came shortly after the politicians appeared in a video in which he criticised himself and the leaders of the Mesa de la Unidad Democrática (MUD) – a coalition of parties that became the largest group in the country's national assembly in 2015 – the local newspaper El Nacional reported.
"To achieve victory, it is necessary to correct some mistakes among opposition leaders,"Ledezma was quoted as saying. "There must be honesty, sincerity among us"
In a separate development, the family of Leopoldo López, co-founder of the Primero Justicia party, has also gone missing, with family members alleging he had been taken away by Sebin members.
Lilian Tintori, López's wife, said on Twitter that members of the security agency took "Leopoldo away from home". López, a political prisoner, had been under house arrest since 8 July.
"We don't know where he is and where they have taken him to. Maduro is responsible", Tintori said in another tweet.
She also posted a video believed to be showing the moment her husband was taken away.
The two opposition leaders' alleged disappearances come one day after Venezuelans voted in a controversial election for a new constituent assembly. The country has been rocked by violence in the lead up the vote.
On 30 July, Maduro hailed the election result, with the government claiming that more than 8 million people – or 41% of the country's electorate – voted in favour of a new assembly that can rewrite the country's constitution and override the opposition-controlled congress.
The opposition, which accuses Maduro of trying to tighten his grip on power, refuted the claim, arguing the election was rigged.
At least ten people were killed on Sunday during widespread protests and clashes with police. Another 58 were detained, according to local media. The opposition has called for further demonstrations.
Venezuela has stirred criticism over alleged human rights abuses and has been hit by sanctions from the European Union and the US.
Last year, the country was suspended from the regional trade bloc Mercosur for violating the organisation's democratic principles. Caracas described the suspensions as a coup attempt. The bloc is composed of Argentina, Brazil, Paraguay and Uruguay.
Following the election result, US ambassador to the UN, Nikki Haley, dismissed the vote as a "sham election", saying the US will not accept an illegitimate government.
One day later, the US Department of the Treasury imposed new sanctions against the president of Venezuela, Nicolas Maduro,